1. Field of the Invention
This invention relates in general to certain new and useful improvements in a means and method for relatively permanently attaching a member to a plastic or glass supporting surface in such manner that the member will separate therefrom when subjected to a high shear force, and more specifically, in one aspect, to a means and method of attaching a rear view mirror device to a transparent glass support in such manner that a high shear force applied to the device will permit separation from the transparent support.
2. Brief Description of the Prior Art
By governmental regulation, essentially all automotive vehicles such as automobiles, trucks and the like are required to have a rear view mirror device located within the cab or passenger compartment of the vehicle. In many cases, and with other forms of vehicles, such as aircraft, boats and the like, the rear view mirror devices are provided for safety purposes, whether or not pursuant to governmental regulation. Generally most vehicle rear view mirrors which are designed for location in the passenger compartment of the vehicle comprise a plate of glass coated with a reflective member such as a silver coating to form a mirror. This assembly is secured within a shell such as a metal frame or housing clipped around the periphery of the glass plate. This assembly is provided with an arm, usually pivotally mounted on the frame and the opposite end of the arm carries a bracket for attachment to the interior of the passenger compartment.
There are several safety considerations in the construction of these mirror devices. First of all, it is desirable to provide an assembly which will not permit the exposure of jagged or sharp edges of the glass in the event of a breakage. This is particularly important in the event of a collision where a person's head or other portion of the person in the vehicle might likely contact the jagged or broken edge of the glass in the event of such impact, whereby severe injury is likely to result.
In addition to the foregoing, it has been found that most automotive vehicle mirrors must be attached to a relatively permanent portion of the vehicle, other than the windshield. There have been several attempts to adhere the rear view mirror device to the automotive vehicle windshield. These attempts generally rely upon the use of an adhesive. However, as indicated above, most governmental regulations require the rear view mirror to shear or break away from the windshield in the event of a high shear force applied to the mirror device as a result of, for example, collision. This is designed to reduce the possibility of injury to the occupants of the vehicle. In any event, most of the adhesives heretofore applied were not effective for this purpose. The adhesive was not sufficient to hold the mirror on to the windshield against a relatively minor shear force. Otherwise, the adhesive was too strong and would not permit the mirror to break away from the windshield in the event that a high shear force, that is, a shear force beyond a desired threshold were applied to the mirror.
One of the principal problems in applying the mirror directly to the windshield is the fact that there has been no convenient means for attaching a plastic layer directly to a glass member such as the windshield itself. Further, and more importantly, when attaching this plastic layer forming part of the rear view mirror construction to the glass of the windshield, it it necessary to permit the rear view mirror device to break away from the windshield in the event of a high shear force applied thereto.